1. Field of the Invention
The present invention relates to a technique to combine a plurality of images.
2. Description of the Related Art
In a scanner configured to read a document, a document size is generally equal to or smaller than can be read at a time by the scanner. For example, when a scanner is capable of reading a document of up to A4 size, the maximum document size readable by this scanner is the A4 size.
In view of the above, a technique has been proposed to read a document with a size greater than the size of a document plate by performing reading a plurality of times to obtain an image of the document part by part. A plurality of images corresponding to parts of the document are combined into a single image, and the resultant image is printed. This technique, however, has a problem that a positioning error can occur among the plurality of images read. That is, in the reading process, when a document is put by a user a plurality of times on the document plate, the position of the document on the document plate can be different each time the document is put. Therefore, if such images are combined, a misregistration among the partial images appears in the resultant combined image.
In view of the above, U.S. Pat. No. 5,732,230 discloses a technique in which a plurality of images read by a scanner are displayed on a display so that a user is allowed to correct relative positions of the respective images by operating the images on the display using a touch screen, a mouse, or the like.
However, among many apparatuses having a scanner such as copying machines, some apparatuses are low in specification, and most such apparatuses do not have a high-performance operation device and a large-size display capable of displaying an image with high viewability. In such low-specification apparatuses, it is difficult to correct relative positions of images obtained via part-by-part reading.